ViewTreeObserver
===

可用來監聽全域 view 的變化

## Ref.
[Android ViewTreeObserver使用总结](https://www.jianshu.com/p/4f68d62c809b)

[RecyclerView加载完数据，获取第一个Item并点击](https://blog.csdn.net/Zmj_Dns/article/details/103871438)

[How to know when the RecyclerView has finished laying down the items?
](https://stackoverflow.com/questions/30397460/how-to-know-when-the-recyclerview-has-finished-laying-down-the-items)
###### tags: `實作相關`